msm: camera: ope: Add a check for valid request in cdm callback

Add a check in cdm callback helper function to make sure
request is valid and same request is not processed again.

CRs-Fixed: 2595373
Change-Id: I3913059671907c6d3b324721d60914962e4e973f
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>